  .one {
    .navbar {
      background-color: 'green';
      background-image: url('https://rescdn.qqmail.com/zh_CN/htmledition/images/skin_27/daytime/top_bg1e9c5d.gif');
      background-repeat:  no-repeat;
      background-size: cover;
    }
   .sidebar-container .scrollbar-wrapper {
     background-image: url('https://rescdn.qqmail.com/zh_CN/htmledition/images/skin_27/daytime/navbar_bottom1e9c5d.gif') !important;
   }
  }
  .two {
    .navbar {
      background-repeat:  no-repeat;
      background-size: cover;
      background-color: 'blue';
      background-image: url('https://rescdn.qqmail.com/zh_CN/htmledition/images/skin_25/top_bg1e9c5d.gif')
    }
    .sidebar-container .scrollbar-wrapper {
      background-image: url('https://img1.baidu.com/it/u=1076841051,68302081&fm=253&fmt=auto&app=120&f=JPEG?w=500&h=721') !important;
    }
  }
  .three {
    .navbar {
      background-repeat:  no-repeat;
      background-size: cover;
      background-color: 'pink';
      background-image: url('https://rescdn.qqmail.com/zh_CN/htmledition/images/skin_16/top_bg1e9c5d.jpg')
    }
    .sidebar-container .scrollbar-wrapper {
      background-image: url('https://img0.baidu.com/it/u=1616885533,1116536101&fm=26&fmt=auto') !important;
    }
  }